The area of a river, or stream, that is adjacent the upstream or downstream end of a dam constructed across the river, where flow over the dam is permitted, is subject to serious scouring or erosion by the flow of water. The flowing water, as it approaches and passes over the dam, creates currents and turbulence in these areas known as the approach and the stilling basin and the turbulence, as well as media carried by the water, scours the bed of the river. Such continuous scouring, over a prolonged period of time can create a large cavity in the river bed, either upstream or downstream of the dam with the cavity eventually reaching such proportions that the structural integrity of the dam immediately adjacent to the cavity, can be threatened. While it has been proposed to place a deposit of riprap, or large size rocks, in the stilling basin to reduce erosion of the river bed, such riprap is itself subject to the forces of the flowing water, and debris therein, and may eventually be displaced or dispersed such that the river bed is subsequently exposed to erosion, at least in areas where the riprap deposit has been disturbed.
It is an object of the present invention to provide an anti-scouring device for an approach and stilling basin that is stable under the influence of the forces acting upon the device.
It is another object of the present invention to provide an anti-scouring device for an approach or stilling basin that can be formed from precast concrete members that can be cast at a location remote from a river and precisely located in the approach or stilling basin, without dewatering the same.